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Do fighter jets use elevators as ailerons?
I saw jets in game using elevators to roll right and left, but I never saw them doing in real life. I was wondering if fighter jets actually use elevator to roll like they do in game.

Related: The moment of a force (the principle of the lever) and the notion of torque.

Jet fighters was invented at the end of WW2 so whatever you take from below as an answer, prepend them with a "Some of them".

Yes.  The airplane’s flight control computer can command a roll using all primary and secondary control surfaces, including differential actuation of the tailplane as Blue Angels #6 demonstrates during a preflight check.

Thank you! Now I found an answer for a question that I had for 2 years!

Yes that exists, the combined elevator/ailerons are called elevons. Particularly delta wing aircraft have them, because the space at the trailing edge of the wing is at a premium. The F-117 had elevons as well, as did Concorde.
Image source
Swing wing designs use elevons as well:

the F-14 Tomcat rolled through elevon and spoiler deflection.
This incident report mentions the elevon of the Panavia Tornado being damaged from a panel coming off.

You may want to add that when the elevon is on the tail (as the OP is asking about), it's typically called a stabilator. At least, that's my understanding.

@yshavit As far as I know, a stabilator is a control surface, usually located in the tail, that serves as both horizontal STABILizer and elevATOR, with no reference to the ailerons. :-)

Don't forget to mention swing wing designs: They use the horizontal tail for roll control as well.

@PeterKämpf Added.

Yes, high performance aircraft prior to the F-15/F-16 era (1970) or so, had a real problem in that attempting to roll the aircraft using ailerons, when at higher angle of attack(AOA) would, because of Adverse Yaw, produce a yaw in the opposite direction, (Stick to the left would produce right Yaw), which, because of the wing sweep, would create a roll opposite the intended direction. This was the cause of many aircraft accidents. The F-100 for example was infamous for something called the Sabre-Dance, where a pilot, by attempting to roll the aircraft using ailerons at high AOA on short final for landing, would induce a roll in the opposite direction, and put the aircraft out of control at very low altitude. The F-4 also had this problem, although by the mid 60s, it was understood well enough that F-4 pilots were trained to use the rudder to roll the aircraft at higher AOA. Instructors, training new pilots, were themselves trained to emphasize this flight characteristic, and, whenever at high AOA, to keep our knees in the back seat right up against the control stick to inhibit new pilots from introducing any aileron.
Before Fly-By-Wire was introduced, this tendency was addressed by having the stabilator, (Horizonal stabilizer and elevator), surface be differentially controllable, and mechanize it so that the fore and aft position of the control stick controlled the degree to which left/right deflection of the control stick would cause aileron deflection vs. differential stabilator deflection.  At low AOA (where control stick was forward), left right motion caused only aileron deflection. At very high AOA (where control stick was aft), left/right deflection would cause mostly differential stabilator. ( I think the first aircraft to use this technique was F-15, where it was implemented using mechanical linkages in the flight controls). Later of course, once Fly By Wire (FBW) was introduced, this was all done by the computer, and it was determined directly from measured AOA, and not just from stick position.
NOTE. The term elevon, is NOT relevant to the horizontal control surface (or surfaces) mounted at the tail of a conventional aircraft design that has a wing AND a horizontal tail. It is only used to describe the horizontal control surfaces at the training edge of the WING on a delta wing aircraft such as the F-102, F-106, Avro Vulcan, Eurofighter Typhoon, Concorde, Saab Draken/Viggen, etc.
The horizontal control surface (or surfaces) mounted at the tail of a conventional aircraft design are referred to as Stabilators, as they are completely movable without an embedded elevator Control surface, and therefore combine the functions of both a horizontal stabilizer and an elevator.

F-14 does this.  It's referred to as a "rolling tail."
In the case of the F-14 this was a solution to dynamics produced by variable wing sweep:

The tail control surfaces on F-14s are known as "rolling tails", in that the aircraft does not have ailerons on the wings to control roll. Roll control is instead provided at low speeds by wing-mounted spoilers and at high speeds by differential horizontal stabilizer deflection.

Here's a frame from the first Top Gun movie showing a real F-14 beginning a hard roll to the right.  The differential deflection of the horizontal stabilizers easy to see:

Yep! Not all of them do, but a good many of them. Off the top of my head I can think of the F-16, F/A-18, F-22, and F-35. They're referred to as elevons.

No they're not. The term Elevon only applies to the horizontal control surfaces at the training edge of the WING on a delta wing aircraft such as the F-102, F-106, Avro Vulcan, Eurofighter Typhoon, Concorde, Saab Draken/Viggen, etc. The horizontal control surfaces mounted at the tail of a conventional aircraft design that has a wing AND a horizontal tail are referred to as Stabilators.

From https://en.wikipedia.org/wiki/Elevon#:~:text=Elevons%20or%20tailerons%20are%20aircraft,aircraft%20such%20as%20flying%20wings. "An elevon that is not part of the main wing, but instead is a separate tail surface, is a stabilator (but stabilators are also used for pitch control only, with no roll function, as on the Piper Cherokee series of aircraft). The word "elevon" is a portmanteau of elevator and aileron."


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Why do brushless motors heat up?
I would like to know what makes a brushless motor heat up. I'm aware of the problems generating the high temperature such as wire contact problems or overloaded motors. I want to know what makes a normal motor in normal conditions warm up. Is it related to the Joule effect?

Because copper has resistance and you have current flowing thru it

https://en.wikipedia.org/wiki/Inductance

Thanks, Koyovis already answered me perfectly, much appreciate to all of you.

"Koyovis already answered me perfectly": It may deserve an upvote.

as i'm a new member i can't upvote it, i specified it to be what i was looking for, and i hope so you guys stop with this way of communication, i'm here to ask a question and you make it seem like a pathetic idea. just stop with over reacting to everything.

The motor is converting electrical energy in mechanical energy, and unfortunately all energy conversions lose some energy to heat. This site states the cause of the heat losses as:

Friction losses due to bearings etc.
Windage losses due to air resistance.
Iron losses caused by magnetic paths of the motor (hysteresis losses and eddy current losses).
Ohmic losses from current flow.
Stray losses: other

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Can a helicopter mask itself from radar?
I have read somewhere that if a helicopter is traveling under 100 km/h and below 5 meters AGL then most radars will ignore it. From what I understand of this process, the radars can pick up things like cars and vehicles driving on the ground and thus need to ignore certain signals if they are traveling below a certain speed and height.
Is this actually the case, though? Does this also apply to military-grade radars?

Edit: This is not asking if a helicopter can fly under the radars coverage, but whether the helicopter can using techniques to notch its signal from being displayed as a contact on a radar operator's screen.

Possible duplicate of Can someone actually "fly under the radar"?

Not a dupe - this question is about seen-but-ignored-as-ground-clutter, while that question is about being unseen by the radar.

Seems like there's a question around primary vs secondary radar here too.

TL;DR answer is "no." If you're in the LOS of the radar it's just about impossible to use stealth geometries in the design of a helicopter (unlike a jet-powered fixedwing craft).

@Carl Witthoft: But it's a lot easier for a helicopter to stay out of LOS, especially in hilly/mountainous terrain.

@jamesqf  then there's the Cruise Missile.

Ever read Tom Clancy Debt of Honor?  AWACS operator saw a fast moving blip right where a high speed train was expected.  He told the system to ignore the blip as a friendly. The high speed train headed out to sea and put a cap in his AWACS.  Also the first couple chapters of Command Authority where a Kiowa drives around on the streets...

@Harper It depends on the sophistication of the radar whether it could figure out that the return is a helicopter rather than a train.  Clancy didn't get all his technology right.

The first shots of Desert Storm were fired by helicopters at radar stations as part of the Suppression of Enemy Air Defenses. For military helicopters, it's their one job, prior to established air superiority. Ironically, the first time the Apache attack helicopter was used in the role it was designed for, it didn't go so well; 2003 attack on Karbala

You can't hide helicopters from Radar on M*A*S*H...

Note that for advanced radar systems, moving helicopters might always be distinguishable from cars and other objects, due to the fact that helicopters have moving rotors.
While I have no information on military systems, I know the systems by robinradar can separate drones from birds by using doppler shift techniques.
Doing this on an actual, full-size helicopter without rotor guards should be a lot easier than on a drone.
This means avoiding detection by moving slow and staying low might not work, unless you can stay out of the line of sight of the radar system.

Wow, that's a good point and I didn't think of that. If the rotor has a unique signature that can be distinguished from other vehicles like cars or birds, then perhaps this masking technique is wrong?

As I understand it, it's not hard to distinguish rotors because the tips move at extraordinarily high speeds, and that causes an evident doppler shift in the rotor reflections. You do need a system that actively looks for it, has a high-enough resolution (= limited distance), and doesn't dismiss it as noise, but I assume the military does, since commercial companies also use it (and for the military it can also be useful to identify dual/coaxial rotors to narrow down model, which is also possible using this technique afaik).

+1 for the robinradar reference. I didn't know that was available commercial.

@ErikA yeah, there should be an identifiable "doppler spread" on the return. A car going +20m/s radially will have almost all of its return at a +20m/s doppler, but a helicopter with the same groundspeed has components moving anywhere between -180 and +220 m/s.

The answer is yes (in most cases) but it has little to do with the helicopter itself. 5 meters (~16.5 feet) AGL is quite low to the ground. Chances are you are simply below the radar horizon for whatever the local radar facility is. At that height you are even below trees, buildings and the like. This of course is affected by the distance to the radar unit as well as having a clear line of sight to it. So being on an airfield or very close to a radar facility you may very well be visible. Military grade radars are bound by the same laws of physics as civilian ones, so yes it applies.
Like any electronic system, radar units are susceptible to noise and do implement filters but they tend to be for general "noise" exclusively filtering out helicopters flying <100km/h and under 5 meters is a somewhat specific constraint.

I think the point is not that there's a specific filter for "helicopters doing less than 100km/h under 5m AGL" but, rather, that there might be a filter for anything doing less than 100km/h under 5m AGL because, otherwise, every vehicle on the road would be causing clutter.

I would expect a large factor to be whether it's ground-based radar or an airborne system.

This is just "flying under the radar" and doesn't count.

The JSTARS (Joint Surveillance Target Attack Radar System) military radar developed and used from 1991 was particularly good at identifying helicopters.
JSTARS was designed to identify moving objects on the ground, such as tank columns and supply convoys used by the Iraqi forces during Operation Desert Storm.  It used a doppler radar suspended below a large aircraft and, as such, it had generally better line-of-sight capabilities compared to ground based radars.  Using doppler, any movement was highlighted, especially the rotational movement of the rotors, which meant that even if a helicopter were sitting on the ground with its rotors idling, it was still seen by JSTARS operators.
Helicopters trying to fly slowly in order to avoid air tracking radar systems would make it far more likely that they'd be identified by a GMTI (Ground Moving Target Indicator) system.

A helicopter is no different from anything else. And radar doesn't care whether you're in a helicopter or whatever.
All the radar cares about is whether you're reflecting energy back to its reception antenna.
A helicopter will do that, IF it's in line of sight to the antenna (and to the sending antenna, which may be somewhere else).
At 5m above the ground, a helicopter or indeed anything would have to be pretty close to the radar installation to do that, not only due to the curvature of the earth but the transmission angle of the radar installation, terrain features, etc..
For example even a low rise in the terrain, like an earthen berm protecting the radar installation, or some trees standing around it, a shack or house in the vicinity, would be enough to hide something from detection.
And yes, many radar installations can be set up to ignore things that don't have at least a certain speed and/or are below a certain altitude. This to prevent cluttering the displays with radar returns from birds, cars, motor cycles, and things like that. But that's a function of the display unit, not the radar receiver. It still gets all those returns, there's just a software filter between it and the screen that declutters the data for easier interpretation by the radar operator, who should have an option to tweak or even turn off that decluttering as needed.

This is a good answer, I just wanted to clarify that in this case I was referring to being displayed as a contact on the users screen (or being engaged by radar guided weaponry).

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Is it possible to power a very small jet using batteries?
I have read a lot of answers on batteries powering large commercial jets, and how it won't work. However, for a small jet like the Honda jet, would it be possible for it to be powered completely by batteries?

Well, if all you want is to taxi around and maybe do a short traffic pattern, then yes. For any practical useabilty: The answer is no.

Is it possible to power a very small jet using batteries?

Yes, with some major provisos.
Jet
It is misleading to use the word "jet" because a jet engine requires combustion of hydrocarbon fuel to create heat to expand exhaust gasses to drive a compressor and produce direct thrust and/or to power a bypass fan. An electric powered aircraft engine would most likely just use electric power to directly drive a ducted fan.

Photo by Varmin CC BY-SA 3.0
Batteries
The Airbus E-Fan prototype first flew in 2014 and was the "first all-electric two-engine aircraft" to  cross the English channel. I don't know what it's range was but assume it was very short. I think 2 hours was expected for later versions but the project seems to be cancelled.

The motors moving the fans are powered by a series of 250-volt Lithium polymer battery packs

These were described by Airbus as Li-Ion 18650 cells with a total battery weight of 167 kg
These battery packs have an energy density of 207 Wh/kg which is 0.745 MJ/kg
By comparison aviation kerosene has an energy density of 46.36 MJ/kg
Hybrids
Airbus seem to be working on an "E-Fan X" hybrid aircraft

Image from Airbus press-release

The E-Fan X hybrid-electric technology demonstrator is anticipated to fly in 2020 following a comprehensive ground test campaign, provisionally on a BAe 146 flying testbed, with one of the aircraft’s four gas turbine engines replaced by a two megawatt electric motor. Provisions will be made to replace a second gas turbine with an electric motor once system maturity has been proven.

This uses a two megawatt generator to power the ducted fan. So the power source, or more accurately energy reservoir, is hydrocarbon fuel, not batteries.
The purpose of this aircraft is to develop electric propulsion technology, it isn't a prototype passenger transport.

On some scale, of course this works -- look up "EDF", Electric Ducted Fan R/C models of jet planes.  For something the size of a Honda Jet, you still likely wouldn't get the performance (and certainly not the range) that you might desire.  Go smaller, and something in the size range of a BD-5J/Acrojet, which originally flew on a very small engine, might support being converted to an EDF -- though the flight endurance would likely still be very short.
EDF would be suitable for a motor glider or self-launch sailplane, neither of which depend heavily on long power endurance for normal operation (but neither of which are expected to fly hundreds or thousands of miles at hundreds of miles per hour, like a Honda Jet).

I think we're getting into a matter of definitions here.  Is a ducted fan a "jet", or is it simply a propellor with a shroud around it?

Same could be said of a turbofan -- effectively a shaft turbine turning a ducted fan, but we call them "jet engines" colloquially.

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How do composite aero structures compare against metallic structures in crash resistance?
is there any information available comparing the difference in crash resistance between composite mainly carbon or fiberglass polymers etc vs conventional metallic mainly aluminum aircraft structures.

"Crash resistance" is an interesting term... I'd think "crash resistance" has more to do with pilot skill than the aircraft's skin material. If, however, you're referring to the ability to withstand the forces applied after things have gone wrong, I doubt there's much difference between the two. Considering flights like Aloha 243, even aluminum is pretty darn strong.

I understood that was a widely used term to describe an airframe's ability to withstand impact forces resulting from a collision. Crash resistant fuel tanks are commonly used on rotorcraft for example. And I would wager that an Isotropic and highly ductile material such as aluminum would handle impact forces differently compared to an anisotropic and brittle material such as CFRP.

Interesting. As I read your response, I got to thinking about F1 cars and how the CF nose cones (and the rest of the car) are designed to splinter to absorb impact vs what the old aluminum honeycomb chassis construction used to do. Now that I think about it that way, that is a very interesting question, and I wonder if any research has been done in this area. "Crumple zones" are a rather curious idea on a commercial airliner, though fuel tanks being resistant to splitting on impact certainly makes sense and has been done.


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Are we changing the angle of attack by changing the pitch of an aircraft?
For example:
if I pitch the airplane up, but also increase power and am able to maintain the same speed, then no, the AoA hasn’t changed, although it may have varied in the transition between one situation and the other. And yes, I’ll probably be climbing, although there are exceptions, becuase…
if I pitch up, slow down, and maintain the same altitude, then undoubtedly the AoA has increased. Flying slower reduces the amount of lift generated. An increased AoA gets that back so I can maintain the altitude.
Can someone explain these situations why exactly are they producing different results in AoA?
Can someone explain these what is going on in terms of forces?

Please explain in reference with these forces ( in the pic )

Any question including such a poorly-drawn diagram as this, really ought not be answered at all, because it is a question with erroneous content included as part of the premise of the question.  Thanks a lot, NASA!

Lift will not change when angle of attack changes and speed is adjusted accordingly to maintain level flight. What does change is the lift coefficient.

This sentence is unclear: "For example: if I pitch the airplane up, but also increase power and am able to maintain the same speed, then no, the AoA hasn’t changed, although it may have varied in the transition between one situation and the other. "  It sounds more like an answer than a question.  If you don't tell us anything about the relationship between the change in pitch attitude and the change in climb angle, then it is impossible to know whether or not the angle-of-attack has changed.  Only if the two values are identical, has the angle-of-attack remained constant.

Initially at the point of pitch increase, Yes.  The formula to understand the relationship between pitch and Angle of Attack is:

Pitch Attitude + Incidence = Angle of Climb + Angle of Attack

The angle of attack will increase the most when you first increase the pitch.  As you establish an angle of climb the angle of attack will begin to decrease.
If you are able to maintain the same airspeed in the climb by increasing power than the angle of attack will return to the trimmed angle of attack.  So if your pitch angle matches your angle of climb then angle of attack will be the same as before the pitch increase.
As you pitch up the thrust vector points upwards and the lift vector points more backwards.  So thrust has to carry some of the weight of the plane during the climb if the same Angle of Attack is maintained.  Generally a decrease in airspeed (thus an increase of angle of attack) is preferred during climb (if on the front side of the power curve) as less excess thrust will be required to maintain a climb.  There will also be less parasitic drag at the slower airspeed.
What is not shown on your diagram is the pitch moment caused by the center of thrust not being aligned with the center of gravity.  This causes a perturbation in the trim speed so retrimming may be needed with power increases.

"Are we changing the angle of attack by changing the pitch of an aircraft"
Yes! Let's start with an aircraft in straight and level steady state flight.
We are taught "pitch controls speed, power controls altitude".
If that was the only input, the nose would rise AND the plane would slow down.  The increase in AOA causes an increase in lift AND drag. The altimeter would show an increase. Forces out of balance.
If the elevator deflection was full, the AOA would increase until stall.  With no power, stall.  With full power either stall or loop! Unless there is sufficient power to loop, there will be a power-on stall.  Pitch does control speed and will increase AoA.
Lower degrees of elevator deflection will result in a climb and loss of speed. This is why pitch and throttle go hand in hand.  Airspeed must be maintained by increasing throttle to continue climb, or the same inexorable process of lower speed and increasing AOA again occurs.  However, with a slight pitch change with no power change, the aircraft may merely slow down a little and climb gently.
But this depends on your airspeed and power setting before you apply elevator.  IF YOU ARE LOW AND SLOW DO NOT PULL ELEVATOR OR YOU MAY STALL.  ADD POWER TO CLIMB.  And keep an eye on your airspeed.

First of all, note that the diagram linked in the question is erroneous.  The equations may be right, but the forces are drawn in the wrong proportion-- lift is erroneously shown as greater than weight, when it should be less than weight.  Also thrust appears to be about equal to drag, when it should be distinctly greater than drag.  Only when lift is less than weight and thrust is greater than drag can we build a closed vector triangle-- meaning that net force is zero-- from weight, lift, and (thrust minus drag ).  For more, see this answer to a related question Does lift equal weight in a climb? .  (If you want to see a similar diagram from an outside source, see the one included in this answer to a related question Is excess lift or excess power needed for a climb? )
Just as NASA also messes up the proportions in this diagram for gliding flight--  https://www.grc.nasa.gov/www/k-12/airplane/glidvec.html -- again, lift is shown as being greater than weight, when it should be less than weight, so we can build a closed vector triangle from weight, lift, and drag.  For more, see this answer to a related question What produces Thrust along the line of flight in a glider?
Now as to your questions-- to a first approximation we can think of our pitch control inputs-- the position we are placing the control stick or yoke in, in the fore-and-aft direction-- as most directly governing angle-of-attack, not pitch attitude in space.  Pitch attitude in space is influenced by the climb angle which is influenced by power setting.  Now, there are all kinds of inter-relationships that complicate things-- for example on a high-wing plane with flaps down, adding power may produce a strong downwash over the tail that tends to lead to an increase in angle-of-attack.  But to a first approximation we can think of our pitch control inputs as governing angle-of-attack.  There is a slight delay between a change in pitch control input and a change in angle-of-attack, due to the aircraft's rotational inertia in the pitch axis.
If I tell you that I've increased my aircraft's pitch attitude by 10 degrees but I don't tell you what I did with the elevator control to make that happen, nor do I tell you whether I've added power or not, then you have no way to guess whether I've kept the angle-of-attack constant and started climbing due to added power, or I've managed power as needed to keep altitude constant while transitioning to a higher angle-of-attack and lower airspeed, or any number of other possibilities-- I might even have put the stick or yoke forward to decrease the angle-of-attack and still added enough power that the aircraft transitioned into a climbing flight path resulting an in increase in pitch attitude.  For example when a jet fighter aircraft is climbing vertically on raw thrust alone, the control stick is probably forward of the position where it would be during horizontal flight at the same airspeed.  Certainly the angle-of-attack is lower in the vertical climb, than in horizontal flight at the same airspeed!
From the standpoint of what is really going on physically with the aircraft, most flight training curricula vastly over-emphasize the idea that the pilot is directly controlling the aircraft's pitch attitude.  What he's really doing is controlling angle-of-attack and power setting.  Yet the former way of looking at things works well enough in actual practice (e.g. flying an ILS glide slope by referring to an attitude indicator rather than an angle-of-attack meter as the primary guide to pitch control) and is simpler to think about.
A key point is that our flight operations are usually conducted on the "front side of the power curve", where for a given power setting, an increase in angle-of-attack usually results in an increased climb rate and an increased climb angle.  Therefore moving yoke or stick aft results in an increased angle-of-attack AND an increased climb angle (or a decreased glide angle) AND an increased pitch attitude. On the "back side of the power curve", like just above stall speed, an increase in angle-of-attack will generally lead to a decreased climb angle or increased sink angle, and the aircraft will end up in a more nose-down pitch attitude, so the idea that we're somehow directly controlling pitch attitude with the control yoke or stick no longer works very well.
Your question indicates a desire to better understand some of the physical relationships at play.  Lift is proportional to (lift coefficient * airspeed squared).  Lift coefficient is determined by angle-of-attack, with higher angles-of-attack creating higher lift coefficients.  As shown in the vector diagrams attached to the two links given at the start of this answer, for shallow to moderate climb or dive angles, lift is NEARLY equal to weight.  Actually, lift is a little less than weight unless the flight path is exactly horizontal, but for shallow to moderate climb or dive angles, the difference is small.  Since weight is staying constant, we can conclude that for shallow to moderate climb or dive angles-- with no other accelerations going on (airspeed is staying constant or changing only slowly, and the flight path isn't curving up or down, and the wings aren't banked so the flight path isn't curving to describe a turn), lift is also staying nearly constant.  This means that for shallow to moderate climb or dive angles, airspeed ends up being a pretty good guide to angle-of-attack-- to keep lift nearly constant, if the airspeed is low, the lift coefficient and angle-of-attack must be high.  So the airspeed indicator is in essence an angle-of-attack gauge.  At very steep climb angles where lift is quite a bit less than weight, things get more complicated-- if the aircraft is climbing straight up, lift must be zero, so lift coefficient must be zero, and angle-of-attack must be nearly zero (actually it must be slightly negative, unless the airfoil is completely symmetrical), no matter what the airspeed indicator reads.
In actual practice in general aviation, commercial aviation, etc, a shallow to moderately steep climb is NORMALLY carried out a higher angle-of-attack and lift coefficient--and therefore a lower airspeed-- than we'd use for high-speed cruising flight.  It's more efficient this way, and it also gives us the most climb performance out of a given, limited amount of thrust available.  Why?  Because a high lift coefficient also correlates with a high ratio of (lift coefficient to drag coefficient), which means a high ratio of lift to drag.  For shallow to moderate climb angles, the higher the L/D ratio we can achieve, the steeper we can climb for a given amount of thrust.  This is explored in more detail in the first link given in this answer. To look at climb rate rather than climb angle, we'd have to look at a chart of (power-available minus power-required) at various airspeeds or various angles-of-attack, but we'd come to a similar conclusion-- our best climb performance will be achieved at an angle-of=attack well above what we'll be using in high-speed cruising flight.
The diagram in the original question doesn't touch in any way on the relationship between airspeed, angle-of-attack, lift coefficient, magnitude of lift vector, and L/D ratio, so it doesn't help us to understand why a shallow to moderately steep climb is normally carried out at a higher angle-of-attack than we'd use for high-speed cruising flight.
Your question included the statement "if I pitch the airplane up, but also increase power and am able to maintain the same speed, then no, the AoA hasn’t changed, although it may have varied in the transition between one situation and the other."  For shallow to moderate climb angles, your statement is true for all practical purposes, but it is not EXACTLY true.  If we want to be very precise about it, we could note that since lift is slightly reduced in the climb, if airspeed stayed constant than angle-of-attack must have been slightly reduced, and if angle-of-attack stayed exactly then airspeed must have been slightly reduced.  This same idea came up in these two related answers to related questions, though in these cases the lift vector was reduced because the aircraft was in a descent rather than a climb -- 'Gravitational' power vs. engine power and  Descending on a given glide slope (e.g. ILS) at a given airspeed-- is the size of the lift vector different in headwind versus tailwind?

Not only the essential proportions are wrong in the diagram, but also the typical proportions like L/D are way wrong. Normally, L (and W) would be 5-15x greater than D (or F). Sometimes it is useful to exaggerate magnitudes/angles, but not in a such educational diagram...

An important point to stress (which everyone just touches) is that you are mostly talking about static, stabilised conditions. During transition, indeed, the pitch control (almost) directly controls AoA, and then this change affects other things, including the final AoA itself. It is important to note because AoA (and pitch, but unlike speed) are 'fast' variables, and their transition/dynamics is a matter of much consideration as well. Assuming static values is a very pilot-centric mindset.

"Yet the former way of looking at things works well enough in actual practice (e.g. flying an ILS glide slope by referring to an attitude indicator rather than an angle-of-attack meter as the primary guide to pitch control)..."-- also, trying to maintain a specific pitch attitude rather than a specific airspeed or angle-of-attack helps to avoid accidental "phugoid" oscillations due to the pilot getting a little out of phase as he "chases" the desired airspeed with his pitch inputs. Yet it remains the case that the position of the yoke/stick/elevator mainly governs a-o-a not pitch attitude.

In your Question, you asked for an explanation the NASA image. As pointed out, the image is incorrect because the Lift vector appears to be greater than the Weight vector.
The reason the image may be incorrect is because it may have been drawn by a person who received training as a private pilot. When I received my private pilot training 30 years ago, I was taught that to climb, you increase lift and increase power. The same thing is apparently being taught today. According to the FAA "When an airplane enters a climb, excess lift must be developed to overcome the weight or gravity. This requirement to develop more lift results in more induced drag, which either results in decreased airspeed and/or an increased power setting to maintain a minimum airspeed in the climb." [Airplane Flying Handbook (FAA-H-8083-3B), p. 3-16] (I removed the reference to the Embry Riddle website, because the FAA quote is enough.)
Not every flight school teaches the subject that way. See, e.g., the webpage for Gleim Aviation.

Re "Regarding the point made in the first answer"-- be aware that different readers will see different answers displayed at the top of the screen depending on whether they have selected to display by "active", "oldest", or "votes".  If you click on the "share" button under an answer or question you will be given a link that you can cut and paste anywhere you want to give a link to that answer or question.

Clearly, the Embry-Riddle Aeronautical University should not be taken as an authority on piloting airplanes-- or at least upon the actual physics that are at play while an aircraft is being piloted!  And likewise, the FAA.

@quietflyer - "likewise the FAA" Yes, but if you are taking an FAA test or an engineering test in which the question appears, you had better be prepared to give the appropriate "right" answer :) FYI, I have had some questions about statements made in that NASA series (specifically relating to drag). But I was told that the person who created them has retired and that there is no one in charge of revising them.

This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review

@Bianfable - I should have deleted that first sentence - since my Answer did respond to the original Question which was "Can someone explain what is going on in terms of forces?" (referring to the NASA image). I am trying to provide some useful background as to why the image was drawn that way and I have rewritten my answer to (hopefully) do a better job of explaining this. As far as I know, I am not asking for any clarification from the Asker. Let me know if you still feel that I should delete my Answer.

@quietflyer - Yes, I did reference the same material in another discussion (only one). I thought that the information about the apparent conflict between Pilots and Engineers regarding Lift would be especially helpful in this discussion since the NASA chart reflects the Pilot opinion. Although I think this background is helpful, I don't plan on adding this tidbit to other discussions as it appears that could be a lifetime effort with little value. Also I think some readers get the misimpression that I am saying that the Engineers are wrong.

@quietflyer Thanks. As an afterthought, I was tempted to alert everyone to the problem with the FAA statements by posting a question asking if anyone is aware of the justification for the FAA statement. However, my experience with StackExchange indicates that the Exchange is more focused on the right Answer and is not really designed to encourage open discussion since the people who disagree with anything they think you are saying can effectively kick you off the Exchange by downvoting you into oblivion. That's too bad because I was actually learning something from our discussions.

PS one option -- I don't know if there's a min rep score needed to do this-- is to create an ASE chat room called something like "A room to talk about question so-and-so" (or once I even created one called something like "A room to talk about hang glider flight dynamics") and then just leave a brief comment "if interested in discussing further, post in this chat room".

Also once two people go back and forth in dialog for a certain number of comments the system automatically creates a chat room dedicated to that question and copies the comments over to there and you can keep talking there for as long you wish and no one will complain--

@quietflyer Thanks for the advice and help. I've fallen below the rep score required to participate in chats so I am going to have to start deleting Answers, such as this one, which have received negative scores.

Let us continue this discussion in chat.

The lift component is reduced when you climb more steeply, that means you need less angle of attack and more engine thrust to fight gravity.
Take this to the extreme: F18 going vertically, you need zero angle of attack and zero lift, your engines are providing enough thrust to counter the gravitational pull.

Not necessarily-- yes the lift vector must be smaller at a steeper climb angle.  But if we start in shallow climb at 100 mph, and we slow to 80 mph while leaving the power setting unchanged, and our best climb angle occurs at 60 mph, there's no doubt that we've increased the angle-of-attack, even though for the reasons given in your answer and mine, we know the lift vector has decreased a little.  Lift depends on airspeed squared, as well as angle-of-attack.  More to the point, for SHALLOW climb angles lift stays ALMOST equal to weight even for substantial variations in airspeed.

Yes going straight up the angle-of-attack MUST be zero.  Yet in actual practice in general aviation, commercial aviation, etc, a climb is NORMALLY carried out a higher angle-of-attack and lift coefficient than we'd use for straight-and-level cruising flight.

For shallow climb angles and dive angles, the airspeed is a pretty good guide to angle-of-attack-- lift is roughly equal to weight (slightly less unless flight path is horizontal, but only slightly less), so a lower airspeed correlates to a higher angle-of-attack.  At steep climb angles things get more complicated.


text:
What kinds of altimeter are used in modern airliners?
What's the mechanism of the altimeters in big jets?

Related: Recent blancolirio video (background and potential interference problems for radar altimeters)

Main instruments
In large aircraft, main altimeters are not separate mechanical altimeters. Instead the pitots, static probes and angle of attack probes, which are redundant, have their outputs digitalized by analog to digital converters (ADM: air data modules):

Pitot/static pressure converter, source
Digital data are send using a bus and processed by air data units, often coupled with the inertial units, sometimes also with GNSS (ADIRU/GNADIRU for Airbus).

A330 air probes and ADIRU, from A330 FCOM
ADIRU are computers, located in the avionics bay:

A330 ADIRU, source
They process probes inputs and compute altitude, airspeed, vertical speed, angle of attack, wind drift, air temperature, etc.
ADIRU information can be displayed on various screens. On large aircraft the content of the screens is managed to cope with failures, information can be rerouted to working displays. In normal mode, data from the left set of probes is displayed on the left seat screens, and data from the right set on the right seat screens.

Source: A330 FCOM
Altitude is usually displayed on PFD (primary displays). Here seen from the right seat:

A330 F/O screen, source: Flickr, photo by swiss_a320

Standby instruments
Analog standby instruments are still fed with air pipes from pitot and static standby probes, in particular the standby altimeter is a barometric instrument, using an aneroid capsule.
Radioaltimeters
A word about radioaltimeters (RA), as they were mentioned in a comment. Radioaltimeters are not altimeters, this is a misnomer, they measure height above ground level (AGL). In aviation, the word altitude is used exclusively for a measure of height relative to mean sea level.
That said, there is not much to say, RA are exactly the same than GA or business jets aircraft. They are used for landing, to evaluate the height above the threshold, in particular the decision height which is the point where the approach must be aborted if all conditions for a landing are not met. As their name implies, this is a radar measure (roundtrip time of a wobble radio signal).
RA are one of the data sources for "one thousand", "twenty", "minimums", etc, callouts (as @Bianfable mentions barometric altitudes can also be used). On large aircraft RA are coupled with the autopilot mode to monitor the approach and trigger various alarms.

Why no radar altimeters?

"angle of attack probes, which are redundant": Wouldn't one wish they had been. https://www.seattletimes.com/business/boeing-aerospace/a-lack-of-redundancies-on-737-max-system-has-baffled-even-those-who-worked-on-the-jet/

@Peter-ReinstateMonica, all versions of 737 have two angle-of-attack vanes; the problem was that the specific system was not reading both of them.

@PhilFreedenberg! "Why no radar altimeters?": I understand the OP question as: What is the difference in altimeter technology between GA and large aircraft (What's the mechanism of the altimeters in big jets?"), but I have added a paragraph. Thanks.

@JanHudec Oh my. What a screw-up. Still, they weren't redundant...

@Peter, they sort of are not redundant for the other purposes either. One is connected to the captain's stick shaker and the other to the first officer's stick shaker. But if one fails, the pilots have to cross-reference the other instruments and decide for themselves whether the one stick shaker activating is spurious or not.

@757toga: In these sentences, "altitude" is indeed a reference to MSL, e.g. pressure altitude is a wording defined in WMO vocabulary: "Standard pressure altitude - Altitude corresponding in the standard atmosphere to a specific pressure."

I would remove the image for a piezoelectric sensor, since that type of sensor cannot typically measure steady state pressure.

@Sanchises: Thanks for pointing out. I replace the image by what I believe is the actual module used on A330 (Honeywell). Do you know the actual transducer technology used?

@Bianfable: Thanks. note in this section I just emphasize RA are not used for navigation like barometric altimeters. The similarity between RA and barometric minimums is another whole topic. However I improved the last sentence to not exclude pressure-altitude from callout sources.

They say "solid state silicon" so my guess would be a piezoresistive sensor measuring the strain in a membrane.

@Sanchises: Yes, "The IPT, HPA/B, PPT, PPT2 and PPTR/E family use a micromachined silicon die with piezoresistive strain gauges.". Source.


text:
Can a F-4 Phantom II pilot control weapons?
In the F-4 Phantom II, can the pilot in the front seat control the weaponry as well, or do they only fly the aircraft?
And can the weapons officer in the back fly the aircraft in emergencies, e.g. if the pilot is unconscious?

Can the pilot in the front seat control the weaponry as well, or do they only fly the aircraft?

Yes, the pilot in the front could control all weapons.

And can the weapons officer in the back fly in emergencies, like, pilot is unconscious or something?

This is more complicated. The USAF F-4's did not have controls for the RIO's (now called WSO's), but the Navy/Marine F-4's did.

The Navy's flight controls were limited, with no control of flaps, and no afterburner. Gear could only be extended using an emergency bottle. So it wasn't ideal.

My guess is that in the event of an incapacitated pilot the Navy WSO would use their controls to get somewhere near the carrier (or nearby land) and then eject.

Have you source ,is it knowledge?

WRONG, About rear cockpit flight controls, you have it backwards. The USAF F-4s back seat did in fact have full set of flight controls. I'm not sure about all Navy Phantoms, but every one I saw did NOT have flight controls in the rear cockpit,.

Do you know why some had them and some didn't?

The backseater in the Navy/Marine Phantoms had no way to fly the aircraft.  The Air Force Phantoms could be flown from the rear seat.  No insult to the Navy, but the guy in the back on USAF Phantoms was far better trained in flying than his Navy counterpart.  It wasn't neglect on the Navy's part, but where it recruited it's rear seat people.  Most were enlisted or Warrant Officer people who had been in the Navy working on radar and communications systems. For some time, the Navy's rear seaters included enlisted personnel as well as Warrant Officers.  I forget the year, but during Vietnam the Navy made an effort to commission its backseat folks... no more enlisted, but there were still a few warrant officers riding in the rear.  The Air Force never used enlisted rear seaters, and didn't have warrant officers (although it has the same authority to create them, it has not made a warrant officer since the 1950's --- I only saw one during Vietnam).  So, both seats in the USAF aircraft were and are commissioned officers.  It's the same plane, but different ideas depending on the service.  Oddly, the USAF Phantom couldn't refuel from a Navy tanker, or vice-versa.  The Navy used a free-flopping female fuel drogue, while the Air Force used a male one, AND a boom operator to steer the thing into the plane's female refueling port.  Go figure!


text:
At take-off, what is the deflection angle of the rudder for the legacy Hornet?
At take-off, what is the deflection angle of the (legacy) F/A-18 Hornet's rudders?

Please don't create new tags, when there are appropriate existing tags already.

Taking off from a carrier or from an airfield?

It's the same .Canada's F18 don't fly from the carrier and rudders is used in the same way.

@GeorgeGeo Please include such information in the question itself.  It is relevant.


text:
Why is the Auto GCAS system on F-16s limited to only 5G?
The automated ground collision avoidance system (Auto GCAS) on the F-16 is set up for only 5G's.

If the system predicts an imminent collision, an autonomous avoidance maneuver—a roll to wings-level and +5g pull—is commanded at the last instance to prevent ground impact.

(Lockheed Martin)
Why is that? Is it enough to pull out from the dangerous attitude? Because of the max speed or minimum level in peace time?

"Roll wings level and pull up at 5g" isn't going to save you if you are already pulling a 5g overbanked turn at 250 feet AGL in a winding narrow valley, like this training exercise in the UK: https://www.youtube.com/watch?v=kT7qrYi8R_M


text:
What's the minimum number of sensors for a hobby GPS waypoint-following UAV?
I would like to develop my own guidance, navigation and control (GN&C) flight software on a Raspberry Pi, for a small hobby fixed-wing UAV. From a physical standpoint, what is the minimum set of sensors/inputs needed to implement plain old GPS waypoint-following?
I understand I have a lot of math to learn, but what is the minimum set of inputs for that math? I have experience with embedded C++ for vehicle entertainment systems, but no knowledge in the aviation realm.

What's your location? I was under the impression most of the developed world only allowed line-of-sight, operator-controlled operation. Is that not the case?

What is allowed is not the same as what is possible.

A raspberry pi is a terrible choice for this: big, power hungry, and far too much hardware and especially software complexity that can fail in impossible to replicate or understand ways.  Practical things like this use a mid-size microcontroller with a free serial port to interface the GPS.

@ChrisStratton so true. Somebody tried controlling RGB LEDs using software clocking of PWM on a Pi, and got quite the dazzle of colors... the answer was "have the Pi command an Arduino to do the actual clocking"...

Along the lines of what Jeffrey was saying, this is indeed illegal in the USA. Hobbyist drones must remain within the line-of-sight of the operator and below 400 ft AGL. And, seriously, unlike many government regulations, there are very good reasons for these rules (namely, the manned aircraft above that level,) so please follow them. Of course, if all of your waypoints are within your line-of-sight and under 400 AGL, then you're good to go.

400 feet and line of sight may seem reasonable, but it severely cripples the usefulness and freedom of the art in areas where the risk to manned aircraft is extraordinary low to nonexistent. What is also up for debate is why municipal and state-level control over airspace is not a thing. I agree with quiet flyer that legality is irrelevant where the question asks for what is possible.

In 2005 a bunch of guys in Canada did something similar (albeit simpler) with a GPS + digital compass + airspeed sensor (pitot tube): http://www.canuck-boffin.net/sonde/index.htm. They have descriptions of the hardware & software they developed on their site. They used a tiny industrial PC (around twice the size of a Pi but i386 at 25MHz) running DOS.

@Steve That is for hobbyist - rules you need to follow to fly without a license (though you now apparently do need to register). If you need to operate your unmanned aircraft beyond those rules you can get training and apply for a drone operator license with the FAA - THEN apply for a waiver of the line-of-sight rule (which I believe is granted per flight plan)

@slebetman This is somewhat off topic, but here it goes: I would like to remove the registration requirement for hobbyists and reallocate commercial drone operator licensing to be strictly a state-level affair (no FAA involvement except setting guidelines, similar to how Commercial Drivers Licensing is done per state as informed by federal guidelines). What actions can I take, what groups share my feelings? I consider it a gross double-standard that we have ultra-lights and paragliders operating with no licensing or registration at all, yet the micro-sphere of flight is harshly controlled.

@Steve I'm not from the US nor live there but AFAIK the main organisation that represents hobbyists (and the only one FAA recognises) is AMA (www.modelaircraft.org) but they're very conservative and as much as possible try to avoid confronting the FAA. For decades the law that gave FAA the power to regulate airspace limits what the FAA can regulate for unmanned aircraft flying below minimum flight altitude (that's where the 400ft comes from) for non-commercial use. This was intended to cover everything from paper airplanes to hobbyist UAV..

.. but lately there has been a group of business interests including DJI, Amazon, Google and a bunch of other companies that is lobbying the government to license and/or regulate the 400ft airspace (because it's valuable to them for their drones). So in the past few years the wording of the law (which has time limits so is periodically renewed/re-approved) was changed to give the FAA the power to require registration. If you don't like it one course of action is to write to your  representative about it

Look into hobby RC flight controllers. Many are open source, and are able to execute waypoint missions completely autonomously using an IMU and an external GPS input.

The absolute minimum for a generalized vehicle that needs to know its position and attitude (orientation) in space is one per degree of freedom. This can be reduced if we have information about the natural modes of the system and their stability.
For simplicity, let's assume a vehicle moving in 3 dimensions, that means a total of 6 DoF:

3 coordinates in space to know the position
3 angles (or similar) to know the attitude

The simplest way to meet these requirements are accelerometers for the XYZ coordinates and gyroscopes for the angles, and these are often packaged together into an IMU. Technically you don't even need an actual GPS as long as you know the coordinates of the starting location, as you can just integrate from it to know your position. This is known as dead reckoning via inertial navigation and it works this way (let's use coordinate $x$ as an example):

You need to know the initial value $x$ and its rate of change: $x_0, \dot{x}_0$
Listen to the values of the $\ddot{x}$ accelerometer.
Integrate the acceleration to obtain the speed: $\dot{x}=\int{\ddot{x}\,dx}+\dot{x}_0$
Integrate the speed to obtain the position: $x=\int{\dot{x}\,dx}+x_0$

Of course this has multiple shortcomings. Real-world accelerometers have noise, gyroscopes have drift, your starting location is probably inaccurate, your vehicle likely needs more data than that to operate and the whole systems I just described had no way of finding itself if it resets in-mission.
For a realistic barebones project like you described you will need:

3 accelerometers (in an IMU)
3 gyroscopes (in an IMU)
3 magnetometers (usually come with the IMU and help keep the previous 2 in line)
GPS (can be bundled with the IMU and you specifically wanted it)

Further data sources are desirable but greatly complicate the FCS architecture, since you need to properly weight the data, after all, you don't want the aircraft to trust the magnetometer more than the gyros and show you a little trick it learned when passing near a magnetic anomaly.
In particular, a Pitot probe is good to have know your airspeed as opposed to your ground speed. An alpha vane is a bit of a luxury and not needed unless you are pushing the flight envelope.
Any ground-watching sensor with sufficient update rate, range and accuracy (IR, laser, LiDAR, acoustic, etc) will allow you to smooth your landings, and which one you pick should depend on your design and budget; they all have pros and cons.

From the coding standpoint, if you are serious about doing this by yourself from scratch, you should look into real time systems, Kalman filters and the vast field of sensor fusion. Also learn some aerodynamics while at it, so that the airframe itself is not a black box to you. You can run an FCS on an Arduino, even for quadcopters, if you are content with just a basic SAS.
There is a large community of hobby UAV builders online that can provide you with an almost off the shelf solution for your FCS (Ardupilot), if you prefer that approach. I personally often find their documentation lacking, so I suggest you at least learn the basics behind what you are doing, to help you navigate the inevitable gaps in the manual. Also, since it is an open source project, you can then fill in those gaps.

With a dynamical model of the system you don't necessarily need as many sensors as there are degrees of freedom in the state. It just needs to be "observable".

@pericynthion correct me if I'm wrong, but unless your DoFs are somehow linear combinations of each other I don't think you can do away with any without loss of information. The $ x,y,z $ axis are orthogonal and while the Euler angles have a singular case (gimbal lock) they provide a minimum sufficient representation of attitude.

@pericynthionif unless of course you mean that we can reconstruct the attitude state from the trajectory and inputs, which is not the case in the practical world.

You are wrong :) although I meant to say "detectable" rather than "observable". It's sufficient to have as many sensors as there are unstable modes of the dynamical system, provided those sensors give adequately orthogonal observations.

Importantly, it is not necessary that the sensors you do have be perfect, nor that your dynamical model is perfect, nor that there are no disturbances (e.g. wind gusts).

@pericynthion fair, it's been too long since I last dealt with control theory. However, I believe that still requires an extra set of constraints, specifically that the controls cannot move the system out of the stable envelope, which for aircraft is pretty hard to do. The model need not be perfect, but it needs to be applicable: the classical longitudinal and lateral-directional modes are valid for perturbations around stable level flight and an aircraft in a flat spin or deep stall may exhibit new modes.

Let us continue this discussion in chat.

@AEhere: thank you very much for all the details and thank you for the integral examples. I now see how the "blind" approach would work and what the sensors are for that In the case GPS is added to the mix, is that where sensor fusion comes in?

A barometer (or other method to measure altitude changes) would also help - GPS can get altitude, but not with the same sensitivity... (I would argue that it is harder to replace with GPS than the magnetometers - If you have the attitude and time, checking GPS will get direction decently, but slower than a (electronic) compass)(Since GPS waypoints are involved, I assume a GPS is compulsory anyway)

@GertvandenBerg fair, but when away from terrain the GPS should suffice, and when close to it you'll need something more accurate that a barometer anyway. I'll include a line on it anyway. Also, GPS-derived speed vectors are decently precise for the hobbyist level.

Long story short: for experimental purposes, it's a good idea to start with a 9DoF kit + GPS.

The Z-axis sensor is divergent in the presence of the Earth's gravity.  If you are higher than you think, you will estimate G to be too high, and you will compute that you are falling, so you will fly ever higher.  Same problem if you are lower than you think.  Then G will be higher than you estimate, so you will think you are pulling up, and compensate by going nose down.  Don't depend on Z.   Also most integrated gyros are actually rate gyros which must be integrated to develop a true angle.  Unfortunately, that leaves you susceptable to the intrinsic DC offset in the sensor. ...

... Without other data you will sense that you are spinning, and generate a real spin to compensate.  Sensor fusion and Kalman filters are the answer here.  Magnetometers may be you friend for estimating and eliminating the rate-gyro DC offset.

@cmm: Sensor fusion and Kalman filters for what inputs?

@GregMcNulty that is a different question, though I will try to add a line when I have the time. Consider asking it on https://robotics.stackexchange.com/, as I am unsure it is a good fit for this site.

It's probably possible with only the GPS receiver, but it wouldn't be easy and you might have to make some compromises on the airframe design to achieve the necessary passive stability.
The traditional set of sensors for this kind of application are, roughly in order of priority:

GPS
3-axis rate gyro
3-axis accelerometer
3-axis magnetometer
pitot
alpha vane or multi-port pitot
beta vane
baro altimeter
laser, radar or ultrasonic altimeter if you want to do autonomous landings

Since this is your first UAV, I would strongly recommend having the first 4 sensors and probably #5 and/or #6 (but maybe use those for diagnostics and analysis rather than control, since they can be a bit tricky with nonlinearities and reliability).

Not so!  #1, #8, and one third of #2 crossed the Atlantic.  See my answer.

@pericynthion: thanks, good info.... which of these would assist with the stability?

If you just want your UAV to fly to a waypoint, you could do it with a GPS sensor alone, if it was based on a very stable aircraft like a "Gentle Lady" or "Radian" r.c. sailplane, as long as you weren't flying it in very strong wind where there was the possibility of the aircraft going backwards over the ground when pointing into the wind and flying at trim speed.  I suppose you would probably want an altitude sensor as well, unless you just want to apply enough power that the aircraft is slowly climbing throughout the autonomous portion of the flight.  Of course, you could just get the altitude information from the GPS sensor.
If you decided to add a 1-axis yaw rate gyro, this would allow for smoother control.  But in the context of a very stable aircraft as your basic platform, you really don't need any more than that, if your basic goal is to keep it simple.
Speaking from the viewpoint of one who has successfully controlled an ultralight aircraft in cloud using only a 1-axis electronic turn rate indicator, GPS, and wet compass-- and the compass was spinning backwards half the time.  Control in specific limited circumstances (i.e. smooth air, not attempting constant circling in thermal updraft, making only very low-rate turns) was possible without the turn rate indicator, and a robot would surely do a better job of this than a human.
Just do sufficient testing to be sure the aircraft isn't prone to severe pitch "phugoid" oscillations at the CG you are using.

So you can do it with a GPS alone as long as the wind stands still and you have an extremely stable aircraft without any disturbances like engine torque, slight asymmetries of the fuselage, etc? Can you provide an example of this working in real life?

Also, you controlled an aircraft with " turn rate indicator, GPS, and wet compass" and the built-in IMU you have in your ears. Granted it is not too accurate and gets saturated easily, but the association fallacy is really grating. -1

"So you can do it with a GPS alone as long as the wind stands still and you have an extremely stable aircraft without any disturbances like engine torque, slight asymmetries of the fuselage, etc? Can you provide an example of this working in real life?" -- just google "free-flight model airplanes" to see what is possible w/ inherent stability.  Which have a single engine and prop so torque is not a non-issue, but it still works.  Eliminate the requirement for the initial steep climb, and it seems trivial to use info from a GPS to fly to a waypoint.

@AEhere pretty much any "trainer" type RC airplane will fly quite fine "hands off" (of the control sticks) in reasonable conditions - it's designed so that you correct a mistake by letting go.  The timescale at which you need to apply course or altitude correction is within the capabilities of a GPS that is maintaining view of a reasonable number of satellites.  That said, a glider is not really the right platform, those are designed for efficiency not stability and so take more active piloting to maintain a course.  Think abstracted Cessna, Piper or Champ with extra dihedral.

@ChrisStratton I have since been educated regarding the controllability of a system, but I still insist that the condition that the craft must remain in the vicinity of it's stable flight regime is a pretty strong one and must be explicitly stated. My main gripe with this answer is not that, however, but the false equivalence: I did it with only x instruments, so a robot can too; totally forgetting the built-in human instruments and capability to react to situations outside the normal envelope.

AEhere - in reality it is the other way around, a robot hitting waypoints and keeping altitude in a bracket has a far, far simpler job than a human RC pilot who needs to repeatedly get the plane turned around before it flies out of sight, has to learn to unmap directions when flying towards themselves, and to see through false impressions of attitude that are easy at certain viewing angles.  These aren't planes that depart from stable flight - most trainers won't even really spin intentionally and most of the "2nd year" configurations will recover with neutralized controls.

@ChrisStratton I'm talking about quietlyer's claim of controlling an ultralight in cloud, not about his comment regarding free flight models. He had a massive advantage over an FCS with the instruments ha claims he had, yet draws an equivalence.

@quietflyer, Fully agree. People advising a multitude of sensors apparently never built a free-flight model. I would perhaps add that for such a stable platform, you only need 1 (rudder) or 2 (+power for altitude) DOF control, and it can be driven straight from the guidance computer. The rest will take care of itself.

@ChrisStratton agree w/ comment about some other platforms being better than gliders.  The high L/D ratio tends to encourage the pitch phugoid.  Also in the foam glider there is lots of flexing.  Will edit at some point.

Perhaps a summary introduction in control theory could help you. From a control point of view, your aircraft is a dynamic system, which can be described by a state and a dynamic model.
The state is simply a collection of variables of where the aircraft is in each point of time. For a full description, you would have the position and attitude in space, as well as their first derivatives. Any other inertia may also have their own state variable; for example, the propeller speed.
The state equations describe how the state evolves in time. From these equations (especially in linearized form), we can distill a number of (eigen)modes. These modes describe a certain behaviour of the system, and come in two forms: stable and unstable modes. A stable mode is a system dynamic that, for a finite input (perturbation), does not lead to any state variable going to infinity. Note that this does not mean that the state variables go back to some constant value: a bounded oscillation can still be considered stable! An unstable mode is a dynamic that for finite input leads to unbounded growth of some state variable.
To see how many sensors you need, you will want a few things. First of all, you want your system to be stable. Obviously, this means that you want to have a set of sensors that can measure any unstable mode (detectability), and a set of actuators that can control unstable modes (stabilizability). There are a number of (possibly) unstable modes, the most important of wich is spiral divergence. Many fixed-wing aircraft have no inherent roll stability, so you will want to be able to sense your roll angle (a yaw rate or heading sensor could work too, due to the roll/yaw coupling). Furthermore, there is simply your linear motion, which is also unstable (this may seem counter-intuitive, but all it means that you can get infinitely far from your initial point by travelling in a straight line). For this, you will want some kind of position sensor (most likely, a GPS).
All other dynamic modes are not inherently unstable in a fixed-wing aircraft, although your particular design may have some additional instabilities, like an unstable phugoid motion, for which you want to be able to measure and control the pitch motion.
So, the absolute minimum is two to three sensors (latitude and longitude and probably roll or yaw), and use feed-forward for all other variables (set trim and power based on desired altitude and speed, and just go for it). In practice, nobody would build an UAV with just three sensors. There are two reasons for this,

Sensor inaccuracy. Measuring attitude is hard. A gyroscope will inevitably drift over time, and as such, you will need some other sensors to correct for this.
Performance. You ideally want to travel in a straight line to the target, not swaying left and right in lazy semicircles while bobbing up and down a phugoid, praying to a suitable deity that the trim- and power settings leave enough margin to go over that mountain on a hot day.

For a hobby UAV, it typically turns out that sensors are relatively cheap, thanks to MEMS. You would typically use a 3-axis accelerometer, 3-axis (roll rate) gyroscope and 3-axis magnetometer (compass), and why not have a barometer and thermometer as well? And since you use a GPS, you might as well use its altitude data. If you use a brushless DC motor, it should be no effort to measure the prop speed. I think you will find it a lot easier to make a working UAV with these off-the-shelf components (and open-source software that is typically written for these sensors) than finding a single-axis gyroscope sensor and writing your own software.
Furthermore, using more sensors significantly simplifies your observability. This is the notion of being able to infer the state of the system from the outputs. In theory, if your model is sufficiently complex, you need very few sensors to estimate the current state (dead reckoning). However, if you can actually measure your states, your model is no longer as important, and your UAV will be able to respond much better and be less sensitive to changes in the environment or the UAV itself.

Inherent roll stability does exist, as a result of dynamics involving sideslip; otherwise free-flight model airplanes would be impossible.

@quietflyer I suppose you must be right. I'll change the answer accordingly.

It's a great answer- but possibly to a slightly different question than the one that was asked!   Please leave it up anyway :)

I really like this answer, but as you can see there is some debate around the stability of the lateral-directional modes. Can the spiral mode be stabilized to a sufficient degree that we can safely eschew it from our sensor needs? Or would a stable spiral mode simply be like roll subsidience, in that roll rates tend to die but the absolute roll remains?

@sanchises: really good info thanks. Which \ how many state equations are needed ?

@GregMcNulty I'm afraid the answer is: as many as you think is necessary to adequately describe your flight dynamics. A good start would be a book on flight dynamics.

GPS
Barometric sensor occasionally recalibrated from the GPS
Tach to maintain constant piston-engine RPM
Gyro for roll stability

These inputs sufficed for an autonomous chain-of-waypoints transatlantic flight sixteen years ago.

Fascinating, thanks for sharing this!

And I bet they could have done fine without the baro, especially with a more recent GPS with a 10 Hz output rate.

@camille-goudeseune: wow very cool....I feel like there were having too much fun with the name of the uav =)

@quietflyer It's not a free flight design, but it does have enough dihedral for coupling roll and yaw, what would you use accelerometers for?  Or why do you care if the wings are level so long as you are going the right way?   I suspect they had a gyro because they didn't have a compass and so needed to use slowly developing GPS heading information for their steering correction.  This was before you could buy a reprogrammable 6-axis strapdown IMU for $15 in a toy store; today of course you'd just go with a 9-axis chip and decide later what is useful, but the question is about minimums.

@ChrisStratton minor nitpick: roll and yaw are always coupled in conventional airframes, what dihedral does here is stabilize the spiral mode, which is the most likely to give you trouble otherwise.

@ChrisStratton later I noticed the link said they had a roll rate gyro.  Really I think you could use either roll rate or yaw rate or canted to sense both as per turn "coordinator" but it might be hard to do entirely without, unless you had more dihedral. In my tests the gyro axis was canted as per turn "coordinator".

Also my comment should have said rate gyro not accelerometer.

The ArduPilot project has probably already done a lot of the work for you, if you're more interested in the end result than in the process of creating it for yourself. Even if you choose not to use their software, there's probably good information regarding which sensors and how many are necessary.

The APM:Plane subproject
Supported controller hardware
A hat for the Raspberry Pi that has a digital barometer and IMU

@craig-s-cottingham: thanks, yes this will be my reference as I go along re-inventing the wheel for learning purposes...


text:
The F16's maneuver envelope is better under 15000 feets but usually they will go much higher altitudes. Why?
The F-16's maneuver envelope is better under 15K feet, but they  go much higher. Why do they put in that compromise position?

The compromised position of being at a higher altitude? A SAM missile gets you at 15,000 feet a whole lot faster than it does at 40,000 feet... Also if dog-fighting, the higher you are the more options you have, 15,000 feet is pretty easy to lose track of when fighting for your life...

What if your target is also there?

Height is energy. See it as an accumulation of easily convertible energy. Also, the view is better up there. And endurance, too.

For most aircraft, the advantage of flying high is that the air is thinner, so you go faster for the same fuel burn.
For fighters, height gives you the ability to dive to gain speed, giving them the option for intercept a lower plane, or run away faster than a lower plane can follow. If they're relying on their own radar, it also allows them to see further around the curve of the earth. As Ron mentions, it also puts you out of range of some SAMs, and gives you more time to react to others.
Lastly, while the F-16's manoeuvre envelope may be better at lower altitude, what matters is the manoeuvre envelope of the aircraft they might have to fight, and the altitude they choose to fight at. The relative difference between the two types is more important than any absolute value.

+1 for the relative difference alone, but the rest also deserves an upvote.

The other fighter's maneuver envelope is better down low as well. But you fight them where you find them, and you both suffer the same penalty up high, so it's a wash.


text:
In a flat spin, does the F-16 use its rudder deflection against the rotation for recovering?
If the H-tail is used in recovery from the flat spin, is the rudder used for stopping the yaw or beta of the F-16?
I know that it is surely used for inverted flat spin, but I believe that the rudder is blanked by the H-tails in upright spin and is not effective.

It is not possible to have the rudder deflection because the huge amount of AOA and control law take that in consideration and cancel (fadeaway) the pilot rudder inputs.Activating the MPO the slabs moved  max in order to get the nose down to lower AOA and after that we can get responses from the rudder .https://www.flightglobal.com/f-16-spin-recovery-technique-invented/15027.article

Is there a source for this information?

It does provide an answer to the question, and provides detail.

I have a really hard time believing that this is really true. But if is-- great answer!  (But please give some source to back it up.)  And if it's not-- then never mind.

https://www.flightglobal.com/f-16-spin-recovery-technique-invented/15027.article

Groovy link, but I'm not seeing the connection to your answer.  All I see is something about "differential horizontal tail" (deflection)..

PS what the heck is an "inlet store" anyway?  They are shoving those things up the nose of the poor airplane?  Like a nose ring (groovy, or not.)??

Traditionally the spin is broken by these methods : applied max rudder against the spin , idle the engine and neutral the stick ,then pull up from the nose down.In F 16is the decoupling the FBW and  push and pull on the stick with no rudder deflection above the 29 AOA.

Sniper pod or another under the inlet , number 5 and 7 pylon

"In F 16is the decoupling the FBW and push and pull on the stick with no rudder deflection above the 29 AOA" -- if this idea is really true that rudder deflection goes to zero above 29 degrees AoA (and I'm not disputing it), you should incorporate it more specifically into your answer, preferably with a source.


text:
Why does the Eurofighter Typhoon have a long arm canard versus the close coupled canard of the Dassault's Rafale or the JAS-39 Gripen?
The Rafale and the Gripen are quite similar but the Eurofighter Typhoon has the canards far forward. I've been told that this was due to the shape of the air intake.
Apparently the Typhoon's air intake was designed to work in combination with thrust vectoring control. This feature was never implemented so I believe the canards may be less effective than other aircraft, in terms of performance, (specifically turn/pitch rate). Am I totally wrong?

Longer arm means less force needed from the canard, so less drag, especially at high speed when lift center shifts backwards and requires more lift from the front. Shorter arm means the wing can benefit more from the vortex. Basically if you want high speed then long, or high manuveribility then short.

Do you have any sources for that? I would have expected quite the opposite.

@hph304j,  no way, this is because vortex from the close coupled canard (Rafale jet fighter)energises the airflow on top side of the wings like vortex generators system ,from that gain agility.Look at videos of the Rafale demo.

@GeorgeGeo but given the fact that user3528438 cleary states that the longer arm means less force for a given needed moment, i would suspect, that the eurofighter can generate a much bigger pitching moment at full deflection than the close coupled canard, which should translate into higher maneuverbility.

The thing is like that ,Canards used in Eurofighter are big  and after initial deflection to give the desired  AoA ,they return in the same angle as airflow  to not overshooot (their movement is not big in flight ).Their main  Role Is stabilisation .

The Viggen was the first canard aircraft ever to be built in production quantities. Its close-coupled canard is fixed, with landing flaps being the only movable part. Its purpose is solely to maintain aerodynamic flow over the wing at high angles of attack and thus enhance both manoeuvrability and low-speed handling. Saab were not able to develop movable canard technology in time, nor was it necessary in order to meet the aircraft specification. Nevertheless, getting the darn thing into production after 60 years of failure was a staggering achievement.
The Gripen, Rafale and Typhoon canards are also used to maintain high-alpha airflow. However theirs have an additional function as control canards. Their own angle of incidence can be varied to help control aircraft pitch directly, to contribute to other more subtle manoeuvres, and (at least in the case of the Typhoon) to minimise radar cross-section.
The further forward a control canard is placed, the smaller it need be to provide sufficient control authority, just as a long rear fuselage allows a smaller tailplane. Its only real issue is that it interferes more with pilot visibility, but its smaller relative size minimises that.

The Grippen canard is, however, also an all-flying control canard. What Viggen has is largely irrelevant for this comparison.

Thanks, I must have read the question wrong. I have edited my answer accordingly, but have left in the Viggen bit as it has got a couple of upvotes so must have interested somebody.

"Nevertheless, getting the darn thing into production after 60 years of failure was a staggering achievement." That sounds like a story, do tell!

@KennSebesta That would need a new question. Basically, avoiding all the pitfalls the canard can offer is hard. By the late 1960s, the credibility gap was not the least of them.

The forward canard of the EF-2000 also interferes with intake aerodynamics. Where else do you have an engine which is directly influenced by pitch control commands?

@Peter, MiG-21, but in a different way. Like any axial (conical) supersonic intake, it's not very tolerant to AoA changes. So the cone moves forward at higher AoA. But instead coupling it with the AoA sensor, it is actually coupled to the stick position (and Mach, of course).

@Zeus That's why I said directly. All belly intakes use forebody compression on purpose to increase trans- and supersonic thrust at high AoA. But in the EF-2000 it is already the canard position by itself, regardless of AoA, which influences thrust.


text:
Why does Turkish Airlines avoid Israel when going to Amman, but not on the return leg?
(flightaware.com)
Last week I was browsing Flight Aware when I came across a Turkish Airlines flight from Istanbul (Turkey) to Amman (Jordan). I noticed that the flight path clearly makes an effort to avoid Israeli airspace. My instinct was that Turkish airlines had some diplomatic issues with Israel and had to avoid their airspace.
Today I came across this post asking what the busiest Turkish Airlines route is, and turns out that the answer is Istanbul to Tel Aviv (Israel). That made me curious about my initial finding. I posted this as a comment on that thread and fellow user @MichaelSeifert pointed out that the return flight, THY813, flies right over Israel.
This leads me to believe that there are some restrictions on flights entering Jordan. Does anyone know anything about this issue or have other similar examples?

Worth checking if they fly around on Sabbath :)

I am not sure anybody but Turkish Airline's dispatcher can give the exact reason, but there is a couple of possible reasons that have nothing to do with politics or safety:

The combination of prevailing winds and ATC fees make it cheaper to fly around in one direction. Either the fees are higher (it's late night) or the winds make the delay shorter.
The airspace might be congested or the ATC capacity reduced for the night so it does not accept the flight plan. Note that due to night curfew at many European airports, many flights leave Europe in the afternoon for a night arrival in Dubai or Abu Dhabi, so it might actually be quite busy at the time (around 11 p.m.).
The local airspace design might complicate the routing. Airliners normally need to stick to defined airways and standard arrival routes. If the available arrival route requires overflying to the south anyway, overflying a bit more and avoiding the Israeli ATC fees altogether might again come out cheaper.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Could flight control be achieved by rotating a wing entirely?
In a typical airplane, one of the main flight control mechanisms are the ailerons/flaperons, which allows one to tweak the lift/drag profile of both wings independently.
I was wondering about the feasibility of achieving similar flight control by means of rotating an entire wing around its lengthwise axis. As I understand it, such tweaking of the aoa would have very similar flight control characteristics as regular ailerons.
Obviously this is a somewhat awkward design mechanically; the point where the wing meets the fuselage is one of the most heavily stressed parts of the airplane, so to add a pivot there takes some consideration. But I am thinking here in the context of an RC plane; where i think just nesting two carbon tubes at the center of lift will work fine.
Some potential advantages are that while the static loads on the articulated part will be high, the forces required to actuate the mechanism could be lower or approach zero, assuming the center of lift can be held reasonably constant. Also, ailerons are aerodynamically awkward and draggy when not in neutral position; moreso than an airfoil tilted tilted from its optimal L/D. Mostly I am just curious though, what something like this would look like in practice.
I cant seem to find anything on google about a design like this, but surely someone must have tried this before? If not, there must be good theoretical reasons I am missing why we should expect this to be a disaster. Is there a search term anyone is aware of that would lead me to similar designs?

Welcome! I think the question has been already asked, but can't retrieve it. Related: Are there any contemporary advantages in favor of wing warping?

@mins This one?

@Pondlife: That a good one, but I was thinking about one where I believe Peter answered something about robustness of the axle.

@qqjkztd! Bingo!

rotary wing aircraft - a.k.a. helicopter

Some fixed-wing aircraft have that 'tilting wing', like the French 'Pou du Ciel', designed in the 1930s and still flying around...

Thanks for the answers guys; hadnt heard of the Pou du Ciel before, but that concept mashes really well with the direction I was thinking in... now i want to build one...

in WWII, the germans designed a high-wing cargo plane with a variable-incidence wing like you describe. this allowed them to construct a fuselage that didn't need a kicked-up empennage (to clear the runway during rotation); instead, when they were ready to take off, they rotated the entire wing and the plane flew off the ground with the fuselage level with the runway. this arrangement had no outstanding performance advantage over a conventional design and was mechanically complex, so it was not pursued further.

@qqjkztd - There are names for these type of model aircraft, most of which are rc gliders. "Wingeron" - the wings control roll, but there's an elevator to control pitch. "Pitcheron" - the wings control pitch and roll, with a fixed horizontal stabilizer instead of an elevator "Pitcheron" models require transmitter "smart" enough to control the wing servo motors independently. The servo response to roll control inputs can be adjusted to get rid of adverse yaw.

@nielsnielsen: Do you happen to know the manufacturer, name or RLM number of this cargo aircraft?

No, I do not. I read about it in a text documenting pre-WWII German aeronautical engineering technology. it was a twin-engine, high-wing, cargo plane developed after the spanish civil war and before or during WWII.

The very first aircraft ever, (the Wright Flyer), controlled roll by twisting the wings. https://wright.nasa.gov/airplane/flyer.html

This question has now been duplicated here (with at least once answer) -- https://aviation.stackexchange.com/q/97242/34686

Yes, it has been tried before and is regularly used on many horizontal and even some vertical tails.
However, in subsonic flight an elevator will offer better efficiency. Only in supersonic designs is the full-flying tail the clearly preferred option.
To move the whole wing needs very strong hinges and actuators, but there were some which did even this:

Mignet HM 14 Pou du Ciel (picture source). It was light and flew slowly enough that moving the whole wing was not an issue.

The Vought F-8 "Crusader" and XF8U-3 "Corsair III" could jack their wings seven degrees up in order to improve fuselage attitude and pilot visibility during take-off and landing (picture source).

Even all-moving outer wings have been tried for roll control, albeit in only very few aircraft. Three I know of (and all of them were built once only) are:

Granger Archaeopteryx,
Short SB.1 glider, and
Short SB.4 Sherpa, the rotated wingtip of which is shown below (picture source).

Just one note on the F8 crusader: the movable wing was actually a design feature to decrease the approach speed of the aircraft in order to better facilitate carrier operations all while providing a good wing for supersonic flight.

@CarloFelicione The same approach speed could be had by rotating wing + fuselage by those seven degrees, with the only difference that fuselage attitude would be seven degrees higher.

I have just come across this site and the question regarding mainplanes with individually controlled incidence instead of ailerons, so I registered and here's my ten-cents worth!
In my opinion, there seems little point in differential movement of the entire wing when rolling torque is best applied near the tips and not at the root, except maybe in small devices like missiles, models or relatively slow moving light aircraft. However, in larger aircraft the complexity and stress of the wing attachment points and insurmountable complications arising from wing mounted engines, fuel tanks, high-lift devices and especially landing gear, I
would certainly favour conventional ailerons as aeronautical development over the years seems to have proved.
However, as to the history of the idea of rotating an entire wing around its lengthwise axis:
There have been several aircraft made using this principal over the years,
starting around 1895 in the USA with Dr. George A. Spratt and later with his son George G. Spratt, they experimented with & built a large number of successful gliders, flying boats, land planes and even flying automobiles as joint ventures with Bendix, Consolidated and Bill Stout.  All were aimed toward stable aircraft and safer aircraft control systems, and all of them used control wings in some fashion.
See Spratt entry in Aerofiles (sorry, it's near bottom of page) http://aerofiles.com/_sk.html
Note that there appears to be some confusion in designations as Aerofiles list only goes up to Model 107, but a Spratt 108 Controlwing (looking rather like a development of the 105, but maybe a typo) is on display in the Mid Atlantic Air Museum here:  http://www.maam.org/aircraft/spratt.htm
Pictures and more info at:  http://1000aircraftphotos.com/Contributions/BlackTed/9933.htm
Next there was the Cornelius LW-1 [X13706] of 1933, that to quote Aerofiles "was an improved version of the earlier Fre-Wing, this one without ailerons, as individually-controllable wings were used in this role".  Side view here:   http://www.aerofiles.com/corn-lw1.jpg
The above mentioned predecessor the Cornelius Fre-Wing [X182W] (spelling as registered but sometimes spelled Freewing). Good three quarter view here:  http://www.aerofiles.com/cornelius.jpg This had variable-incidence parasol wing panels hinged at the centre section, but also had "Trailing ailerons" that actually appear to be aerodynamic tabs mounted on mini booms (presumably operated by the pilot to drive the pivoting wings rather than directly, which may have been too coarse and less controllable, but that's just my conjecture though as I have never seen any photos of this or the LW-1 in flight with differential incidence on view).
Maybe the most modern that I have seen is this French creation, Daniel Dalby's "Dragon One" picture and info here: http://www.pouchel.com/english/index_eng.php?p=dragon_eng.html
which it is said was possibly inspired by his earlier APEV Pouchel II
There's a brief video here

There's no real sign of the differential action :-( but at only +2°/-4° I guess it won't be too obvious!  However, it does look quite stable, but I would have loved to have seen it turn and bank away! :-)
As the name of its predecessor translated to "Ladder Flea" and Spratt's flying car was nicknamed Flying Flea, I delved a bit on that theme and found this interesting site
https://sites.google.com/a/flyingflea.com.ar/www/home/traditional-fforg-menu-1/spratt
It is mostly about Spratt's work and some others I've already mentioned. However, there are numerous links that I haven't explored yet and right at the bottom a link to a modern UAV and mention about a manned version, the Schmittle Aircraft Freewing MK-5 but the link is dead!  However, these "Freewings" appear to be more of a self-controlled stability augmentation and stall prevention devices rather than a direct means of control and needs further digging :-)
I hope that this post, although it may not directly answer the initial question posed, it should help in showing the various attempts made to use the principle over the years.
Cheers,
TC

Could you remove some of the fluff and get to the point a little more please?

@dalearn: Eelco Hoogendoorn asked the question about "flight control by means of rotating an entire wing around its lengthwise axis" and concluded by saying "I cant seem to find anything on google about a design like this, but surely someone must have tried this before?"  As most of the answers above referred to wing warping or changing the incidence of the entire wing, not rotating the wings independently, my "Fluff" answers and illustrates his latter question, but I take your point, I do tend to waffle a bit :-)

The content is fine in my opinion, it is just the extra stuff that is unrelated to the answer that I was asking about.  e.g. perhaps you could get to the point a little faster or format your answer so that it is helpful for the next person who comes along.

Thank you for adding not one but several designs!

This has been done quite a bit on model airplanes, best suited for slope-soaring gliders or small aerobatic powered planes. It means that full control can be achieved using just two servos and no (weighty) linkages to the tail surfaces. See:

for a beautiful example applied to an antique model design. The servos are externally mounted under the wing leading edges. A carbon wing joining rod serves as the hinge.

Rotating an entire wing to do the job of an aileron is overkill. Ailerons as they have been designed for years can flip a plane 90 degrees from horizontal in less than a second.
Why go thru the hassle when a small control surface will do the job without the huge expense of design?

Charlie Kaman applied your point to rotary wings, and it worked.

My initial question was mostly academic; to deepen my understanding. You are right that rotating the entire wing around the root is indeed probably a poor idea on first principles, since it will require a very heavily loaded yet actuated joint. There are ways to design around that as the pou du ceil shows though. And ailerons have their disadvantages, such as draggy non smooth flow when extended, and loss of control in a stall.

The very first aircraft to fly, (The Wright Flyer) controlled roll by twisting or warping the wings.


text:
How are military aircraft directed to targets?
How would a controller, say, AWACS or ground radar, direct via voice an aircraft to the location of an airborne target?
I've seen it in movies, but don't know if they where right, nor did I understand it.

At least for ground targets, the 9-Line system is used. This describes the target’s location in coordinates, the approach and departure directions, the target’s description, the munition to use, and maybe some other info. Air controlling may be similar?

The controller has radar ID of both aircraft. The radar display used is 'smart' in that it can plot the direction and speed of flight of the target and attack aircraft. It then is a simple matter to direct the attacker on a course to intercept the target.  At least that is how I did it, once.

I figured such but was looking for terminology like how the bearings are stated.